This application claims the priority of German Application No. 198 30 974.0 filed Jul. 10, 1998, which is incorporated herein by reference.
In the cold starting of an internal-combustion engine driven according to an Otto-process, during the first, approximately 40-second phase, significantly increased quantities of hydrocarbons are discharged into the atmosphere. The reason therefor resides mainly in the fact that the catalyst forming part of the gas exhaust system has not yet reached its operating temperature, and thus the catalytic conversion of the pollutants in the exhaust gas, particularly hydrocarbons, nitrogen oxides and carbon monoxide is performed only insufficiently. Such an increased hydrocarbon emission is reduced only in the course of the successive operation, in response to the increase of the operating temperature of the catalyst.
It is an object of the invention to provide an improved method of cold starting which reduces the pollutant emissions immediately upon cold starting of the internalcombustion engine.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the method of cold starting an internal-combustion engine includes the steps of rotating the engine crankshaft by a starter motor to initiate cold starting; and during initial work cycles of the cold start, controlling, by an engine control device, the cylinder valves, the fuel injection device and the ignition device belonging to at least one selected cylinder, such as to operate the selected cylinder with a xe2x80x9cdelayed intake openingxe2x80x9d mode.
Expediently, during the subsequent work cycles the cylinder valves may be controlled in the xe2x80x9cearly intake openingxe2x80x9d mode.
xe2x80x9cDelayedxe2x80x9d or xe2x80x9cearlyxe2x80x9d intake opening modemeans that an intake valve of an engine cylinder is opened by the engine control later or earlier than themoment the piston reaches its upper dead center upon completion of the exhaust stroke. Operating an engine in such xe2x80x9cdelayedxe2x80x9d or xe2x80x9cearlyxe2x80x9d intake opening mode is conventional by itself and is explained in detail, for example, in U.S. Pat. Nos. 4,700,684 and 5,211,146.